Conventionally glass container manufacturing machines, as for example the well known I.S. or individual section machine, comprise a number of pneumatically operated mechanisms. Such mechanisms are controlled by numbers of pneumatic operating valves, and conventionally these pneumatic operating valves are arranged in a valve block and are caused to operate by pilot air provided from solenoid operated pneumatic pilot valves in the valve block.
Known solenoid operated pneumatic pilot valves comprise a manual override which, when operated, moves the pilot valve into an open condition and holds it there, overriding electrical actuation of the solenoid, thus ensuring that the associated operating valve is supplied with pilot air and is held in an activated position and the mechanisms thus supplied with compressed air whatever electrical signal is sent to the pilot valve. This is frequently necessary if a mechanism is to be adjusted or repaired. However, if it is desirable to ensure that the mechanism is not supplied with compressed air, should that be the appropriate condition for adjustment or repair, this cannot be achieved through the pilot valve but instead a physical interruption by way of a stop cock must be made in the supply of air to the operating valve. This physical interruption can be time consuming and difficult on occasion depending on the location and accessibility of the stop cock.
It is one of the objects of the present invention to provide a pneumatic valve suitable for use as a pilot valve which may be mechanically locked in both a position in which it supplies air and in a position in which it does not supply air.